The energy needed to operate a power network is supplied by several different types of power plants such as, for example, nuclear power plants, coal-burning power plants, natural-gas power plants, wind power plants, biogas power plants, or solar power plants, all of which feed energy into a non-local power network. Non-local power networks are, for instance, transmission networks such as those operated in Germany, for example, by Amprion, 50 Hertz, Tennet and TransnetEnBW. These transmission networks are part of the European interconnection grid. Up until now, a network frequency of 50 Hz has been used in these networks in order to stabilize the network. Within the scope of the expansion of renewable energies, there is an ever-greater trend towards reducing the number of turbine power plants (referring here to power plants with turbines for generating energy and feeding it into the grid). As a result, correspondingly fewer turbines of turbine power plants will feed power into the network and will thus have correspondingly less influence on the network frequency. When the load in the network increases, the turbine shafts of turbine power plants are decelerated in order to release energy, so that normally, the network frequency decreases. Conversely, when the load decreases, the rotational speeds of the turbines rise and thus, as a rule, the network frequency also increases. However, when it is mostly network inverters that provide the power during the power production using renewable energies such as, for instance, wind power plants, biogas power plants, or solar power plants, then the amount of power no longer influences the network frequency, so that switching the turbine power plants on and off can no longer be regulated on the basis of an increase or decrease in the network frequency. In this case, the network no longer responds to a change in the load state by changing the network frequency, but rather, the network inverters are switched off abruptly in case of an overload, which could lead to a global blackout (power failure in major power grids).
Before this backdrop, it would be desirable to have a power network that is sufficiently safeguarded against a power failure (blackout), even in case of a reduced number of turbine power plants.